Warning signs are employed in a wide variety of different applications. One important application concerns the safety of highway motorists and pedestrians. It is important to alert both motorists and pedestrians that extra care should be exercised at a particular location. Such warnings may arise from conditions which are either temporary or long term. Long term operations are typically accommodated by vehicular barriers, fencing and similar provisions, while temporary situations require special consideration. A temporary situation may arise, for example, when a work crew is dispatched to a location at or immediately adjacent to a roadway. For example, motorists and pedestrians both are accustomed to seeing utility work crews at roadside locations, from time to time. It would not be appropriate, in these instances, to require fencing or other barriers to be erected to provide a warning that extra care should be taken at the immediate location. Rather, lightweight warning systems are employed that are quickly and easily erected and stored from day to day or even within a portion of a workday. Temporary warning signs have been developed for this purpose. For example, a warning legend may be imprinted on a flexible panel having a cloth or other flexible substraight. Such panels may be coated with a reflective material to further improve their ability to warn nearby motorists and pedestrians that they are entering a location requiring that extra care be taken.
Sign stand systems for use with flexible sign panels have been developed. Typically, the flexible sign panel is folded into a roll when its use is temporary suspended. Upon arrival at a worksite, the flexible message panel is unrolled and flattened into a generally planar or sheet-like configuration. A sign stand system is then erected to support the panel in a generally flat or taut condition that is conducive to enhance legibility. While virtually any type of backing support may be provided, it is generally preferred that the sign stand system also be capable of breakdown for storage into a relatively small sized package. It has been found popular in this regard, to provide braces for sign panels that are made of strong, but lightweight materials such as fiberglass ribs. A ground-engaging stand is provided, usually in the form of a ground post or a multi-legged support system that can be folded when not in use. Typically, one of the ribs is arranged in a vertical position and the bottom end of the rib is engaged with the base of the sign stand. In use, the ribs are expanded and engaged with the sign stand base. After unrolling, the sign panel is attached to the ribs preferably in a stretched or taut condition.
As mentioned, warning systems are often times employed adjacent to a roadway, and thus are subjected to buffeting forces arising from motor vehicles passing nearby. Of course, the sign panel also absorbs energy from applied wind loadings. The sign stand base is often times spring loaded to absorb these forces so as to maintain the sign panel relatively immobile.
It has been found important, that despite the proven performance and wide-spread acceptance of light-weight message systems, that additional warning indication be provided. Typically, sign stand systems are designed to maximize the sign panel area that can be reliably supported, despite buffeting from traffic and applied wind loads. Accordingly, it would not be appropriate to enlarge the “sail area” of the message panel with additional devices visible to nearby motorists and pedestrians. One expedient that has been preferred over the years is to affix one or more warning flags to the sign panel system. Flags have the advantage of utilizing applied wind loads and roadside buffeting converting the applied loadings to movement of the supported flags, a strategy that can not be used with the message panel which must be maintained relatively immobile so as to guarantee proper orientation to oncoming motorists and pedestrians.
While flags may be added to the sides of message panels, it is generally preferred that the flags be mounted at the top of the sign stand system so as to extend above the message panel. A variety of flag mounting arrangements have been provided over the years. For example, in U.S. Pat. No. 5,895,024 assigned to the assignee of the present invention, a bracket is provided at the top of a sign panel to support one or more warning flags that extend above the sign panel. When three flags are provided, the central flag is removable from the bracket of the sign panel system, with the remaining flags permanently connected to the bracket for pivoting between display and storage positions. U.S. Pat. Nos. 5,725,186 and 6,381,889 provide brackets with individual positions for multiple flags.
Several patents provide arrangements in which one or more flag staffs are permanently secured to a sign panel system. The following patents provide permanent pivotal attachments for flags selectably movable from an upright display position to a storage position, where the flag staffs are aligned with a vertical sign panel rib, in preparation for rollup and storage. Included are U.S. Pat. Nos. 4,980,984; 6,045,110; 6,047,941; 5,829,178; 5,832,866; and 5,829,178. U.S. Pat. No. 5,152,091 provides a bracket at the top of a sign stand assembly to which flag staffs are permanently pivotally mounted for rotation parallel to the message panel. Arms project outwardly from the bracket in a direction generally perpendicular to the plane of the message panel to provide stops for the flag staffs, preventing their unintentional collapse, once erected in an upright position at acute angles to the vertical. Problems have been observed with this latter type of arrangement. As mentioned, the sign panel system and any warning flags attached thereto are subjected to buffeting from nearby traffic as well as wind loading. These forces are also applied to the warning flags and these forces can be considerable, especially when energetic wind gusts repeatedly pound against the warning flags and their flag staffs. With repeated loading and vibration due to wind forces, the arms, which normally provide position stops for the flag staffs, have been observed to wear away at the flag staff edges, causing premature deterioration of the flag staffs, and hence requiring accelerated maintenance.
Despite the advances made in the field of flag displays and other types of warning devices associated with highway warning systems, further advantages in cost and manufacture are still being sought.